Our invention describes a novel, economical process for preparing 2-campholenylidenbutanol by means of reacting the compound having the structure: ##STR3## with hydrogen in the presence of a copper chromite catalyst over a specific range of reaction conditions.
There is a continuing search for materials having desirable fragrance properties. Such materials are used either to replace costly natural materials or to provide new fragrances of perfumed types which have not heretofore been available. Especially desirable qualities for substances having interesting fragrances such as sandalwood-type fragrances are stability and persistence, particularly in a wide variety of perfumed articles (e.g., soaps, detergents and powders), perfumed compositions and colognes, ease of manufacture and intensity of aroma.
Furthermore, according to Guenther [E. Guenther, "The Essential Oils", Vol. V. page 173, D. Van Nostrand Co., New York (1952)], East Indian sandalwood oil "has been perhaps one of the most precious perfumery materials from antiquity down to modern times, and its popularity has shown no signs of waning." This oil is widely used in perfumery, and would be even more widely used except for its limited supply and high cost.
As is well known, a need exists for synthetic substances which can be used as sandalwood substitutes or extenders. It would be most desirable to be able to synthetically provide the major odorant compound of the natural sandalwood oil, i.e., alpha-santalol and beta-santalol, but no commercially feasible route to these chemicals is known at this time.
It would be even more desirable to provide a synthetic compound which would have many of the desirable odor qualities of a fine East Indian sandalwood oil, yet not have the potentially labile primary allylic alcohol group present in the natural santalols. A compound which would be more resistant to acidic or oxidative decomposition as well as being base stable could be even more versatile than sandalwood oil itself.
There is no obvious explanation why only slight chemical changes should have such a dramatic effect on odor intensity other than to invoke the general unreliability of odor structure relationships. Why the addition or removal of a methyl group, the removal of a double bond or the mere moving of a methyl group would essentially destroy more than 90% of the odor intensity rather than merely cause subtle odor differences comparable to the subtle chemical differences cannot be explained by any theoretical concepts in the known art.
U.S. Pat. No. 4,052,341 issued on Oct. 4, 1977 provides a sandalwood type aroma imparting material having one of the structures:
TABLE I ______________________________________ NAME STRUCTURE ______________________________________ 3-Methyl-5-(2,2,3- trimethylcyclopent-3- en-1-yl)pentan-2-ol ##STR4## 3-Methyl-5-(2,2,3- trimethylcyclopentan-1- yl)pentan-2-ol ##STR5## 5-(2,2,3-Trimethyl- cyclopent-3-en-1-yl) pentan-2-ol ##STR6## 6-(2,2,3-Trimethyl- cyclopent-3-en-1-yl) hexan-3-ol ##STR7## 4-Methyl-6-(2,2,3- trimethylcyclopent-3- en-1-yl)hexan-3-ol ##STR8## 3-Ethyl-5-(2,2,3- trimethylcyclopent- 3-en-1-yl)pentan-2-ol ##STR9## 3-Methyl-5-(2,3,3- trimethylcyclopent-3- en-1-(R)yl)pentan-2-ol ##STR10## 3-Methyl-5-(2,2,3- trimethylcyclopent- 3-en-1-(S)yl)pentan-2-ol ##STR11## 3-Methyl-5-(2,2,3- trimethylcyclopent- 3-en-1-yl)pent-3-en-2-ol ##STR12## ______________________________________
These materials are produced according to the reaction schemes:
TABLE II __________________________________________________________________________ ##STR13## ##STR14## ##STR15## __________________________________________________________________________ (a) R.sub.1 = H, CH.sub.3, C.sub.2 H.sub.5 R.sub.2 = H, CH.sub.3
East German Pat. No. 68,936 discloses for use in the sandalwood area a compound having the structure: ##STR16## Furthermore, Chemical Abstracts Volume 72, 125008b sets forth a genus for the East German Pat. No. 68,936 encompassing the following group of compounds: ##STR17## wherein R=CH.sub.2 OH, CHCH.sub.3 OH and R.sup.1 =H, CH.sub.3 or C.sub.2 H.sub.5.
Furthermore, U.S. Pat. No. 4,210,767 issued on July 1, 1980 discloses the process for preparing aldehydes and ketones according to the reaction scheme: ##STR18## wherein x is 0 or 2; wherein one of the lines + + + + + + is a carbon-carbon double bond and the other of the lines + + + + + + is a carbon-carbon single bond; wherein A' is one of hydrogen, C.sub.3 C.sub.2 H.sub.5 or --CH.sub.2 -- and B' is hydrogen, CH.sub.3, C.sub.2 H.sub.5 or --CH.sub.2 ; n is 0, 1 or 2; each of the dashed lines represents a carbon-carbon single or no bond; with the proviso that A' and B' is both --CH.sub.2 -- when n=1 or n=2 and the dashed line represents a carbon-carbon single bond; and A' is hydrogen and B' is C.sub.2 H.sub.5 or CH.sub.3 or A' is CH.sub.3 and B' is CH.sub.3 or C.sub.2 H.sub.5 and n is 0 and the dashed line represents no bond comprising the steps of intimately admixing campholenic aldehyde with a ketone having the structure: ##STR19## in the presence of a catalyst selected from the group consisting of zinc acetate and zinc acetate dihydrate; said reaction being carried out in the liquid phase at an elevated temperature sufficient to produce the desired product.
U.S. Pat. No. 4,210,767 further describes the process step according to the additional reaction scheme: ##STR20## wherein M is alkali metal selected from the group consisting of potassium and sodium, comprising the steps of admixing an alkaline metal borohydride with the ketone reaction product having the structure: ##STR21## wherein X has the structure: ##STR22##
Nothing in the prior art shows such a process, however, utilizing a copper chromite catalyst whereby a novel reaction product is produced.
Copper chromite catalysts of the formula: EQU CuO.CuCr.sub.2 O.sub.4
are described in the catalogues by their manufacturers, to wit:
(i) Harshaw Chemical Co. of Beachwood, Ohio 44122, entitled "Harshaw Catalysts" and PA0 (ii) Calsicat Division of Mallinchkrodt, Inc. of Irie, Pa. 16503-2497, entitled "Catalysts From Calsicat".
At page 8 of the Harshaw catalogue it is stated:
"Copper chromite catalysts find application where reduction of functional groups are desired while maintaining the unsaturation of aromatic rings or alkyl chains."
The Calsicat "Catalysts" catalogue states, inter alia:
"Copper Chromite Catalysts . . . Applications include the hydrogenation of aldehydes . . . "
Nothing set forth in the commercial literature pertaining to the copper chromite catalysts suggests the use of the copper chromite catalyst in the reduction reaction: ##STR23##